Cracking of hydrocarbons in the presence of halogen-containing sensitizers



PERCENT PRESSURE INCREASE Filed Jun 11, 1945 July 8, 1947.

p-aurm'e DECOMPOSITION AI' soon:

I2 3 4 5 6 1.6 9 IOII l2 l3l4l5 l6 l1- l8 l9 20 TIME (MINUTES) 7 y 1947-H. o. FOL KINS ET AL CRACKING OF HYDROCARBONS IN THE PRESENCE OFHALOGEN-CONTAINING SENSITIZERS 3 Sheeis-Shent 2- Filed June 11, 1945n-BUTANE DECOMPOSITION AT 500C I2. I TIME (MINUTES) Fiy. 2

nww w u o INVENTORS away? 8 ac 81' BY ATI'J R NEY V Patented July- 8,1947 UNITED sTAjT CRACKING or nrnnocannons IN m I PRESENCE ornanocamcon'mmmq K SENSITIZERS Hillis 0. Folkins, Skokie, and Carlisle M.Thacher, Highland Park, 111., asaignors to The Pure Oil Company,Chicago, 111., a corporation of Ohio Application June 11, 1945, SerialNo. 598,70

i In Canada February 24, 1945 16 Claims. (Cl. 196-52) This inventionrelates to cracking of hydrocarmethod for converting higher boilinghydrocarbons into lower boiling hydrocarbons and for making unsaturatedhydrocarbons from saturated hydrocarbons.

We have discovered that if thermal conversion of hydrocarbons is carriedout in the presence of a. small amount of apoly-chlorinated aliphaticorganic compound, particularly a poly-chlorinated hydrocarbon of theparaflin series in which some or all of the hydrogen atoms in thehydrocarbon have been replaced by chlorine, admixed with a small amountof bromine or iodine or both, the cracking of the hydrocarbon is greatlyaccelerated so that it is possible to obtain larger yields of crackedhydrocarbons under the same time-temperature-pressure conditions than itis possible to obtain in thermal cracking of the hydrocarbons withoutsensitizer, and it is possi-' ble to obtain yields at lower temperatureswhich are commensurate with yields obtainable at higher temperatureswithout sensitizers. Our invention is applicable to either batch orcontinuous methods of cracking. In continuous cracking methods byoperating under usual thermal cracking conditions in the presence of asensitizer, not only can increased yields be obtained but higher octanegasoline can be produced. By using a sensitizer, a larger throughput ofcharging stock through a given size unit can be effected because bonsand is more particularly concerned with a In accordance with theinvention, a small 2 showing. the unexpected results obtained from usinga combination of bromine and propylene dichloride as sensitizer; and

Figure 3 is a graphical representation of data showing the unexpectedresults obtained from using a combination of bromine and1,2,3-trichloropropane as cracking sensitizer.

amount of a poly-chlorinated aliphatic hydrocarbon, such as chloroform,carbon tetrachloride, ethylene dichloride, propylene dichloride, and

' 1,2,3-trichloropropane, and bromine and/or iodine of the accelerationin the cracking reaction I vide a method for improving thermal crackingof hydrocarbons. I 1 Other objects of the invention will become apparentfrom the following description and the ac companying drawings, of whichFigure 1 is a graphical representation of data showing the unexpectedresults obtained from using a combination of bromine and chloroform ascracking sensitizer;

Figure 2 is a graphical representation of data heavy naphtha, kerosineand gas oil. The comare mixed with the hydrocarbons subjected todecomposition. The poly-chlorinated aliphatic hydrocarbon and thehalogen may be mixed with the hydrocarbons prior to charging them to thereaction zone or they may be injected directly into the reaction zone.The total sensitizer mixture may be used in concentrations fromapproximately .055 mole percent to 5 mole percent based on the totalcharge and should contain not less than about. .005 mole percent ofbromine and/or iodine, and not less than aboutv .05 mole percent ofpoly-chlorinated aliphatic hydrocarbon. Higher concentrations ofsensitizers may be used, but within the limits above set forth thereaction progresses rapidly without causing accumulation of undesirablylarge amounts of the sensitizers and their decomposition products in themotor fuel or other product which it is de sired to produce. In ourexperimental workit has been found that a mixture containing from .03mole percent of bromine up to 2 mole percent of bromine and from .25percent of a poly-chlorinated aliphatic organic compound up to 2 percentof a poly-chlorinated aliphatic hydrocarbon gives unusually goodresults. When cracking hydrocarbon oils to gasoline boilinghydrocarbons,

it is preferred to keep the combined amount of catalyst below 1% byweight based on the oil cracked.

The invention is useful in conjunction with conventional types ofthermal cracking in which the hydrocarbons are cracked at temperatureswithin the range of approximately 375 C. to 750 C. and is applicable toconversion of hydrocarbon gases such as propane and butane as well as tothe conversion of liquid hydrocarbons such as bination of the bromineand/or iodine with a poly-chlorinated aliphatic hydrocarbon acceleratesthe cracking reaction to an extent far inexcess of that which would beexpected from the additive efiect of the poly-chlorinated aliphatichydrocarbon and the bromine or iodine alone.

. In' order to demonstrate this fact a number or runs were made usingnormal butane as charging stock. The butane had a purity of 99%. Theruns were all made in a Pyrex glass reaction vesselat a temperature of500 C. Before starting each run the reaction vessel was heated to thedesired reaction temperature and then evacuated by means 01' a vacuumpump to a pressure below 0.001 mm. of mercury. Suiilcient butane inadmixture with the desired amount oi sensitizer composition was thencharged to the evacagainst time.

4 the end 01 the run. The figures app a ing in the table for 5% and12.5% pressure increases were taken from curves of individual runs inwhich percent pressure increases were plotted In the table the figuresgiven under the heading Time in minutes for AP of 25% are in some casesrecorded and in other cases are interpolated from curves based onrecorded pressures because in certain runs the pressure rose aboveincrease too rapidly to obtain a reading at the exact point.

Table 0001111001- Z ZQEB" Sensitization rat-tom 1100001011 Products,Mole Per cent Run Na. 5

Name im}. 0% 12.0% 20% 0% 12.0% 20% 00, 1111000. 00 m Residue 7.41 21.0013.32 i 0.1 20.0 0.3 1.1 100 0. 20 1. 0 00 10 00 0.1 0.1 4. 0 0.1 24.10. 3 1. 0 14.0 0.0 1.00 4.10 11.02 1.4 0.0 0.2 0.0 23.1 0.0 0.0 70.1 1.00.41 4 2.10 0.13 10. 1 10.1 0.0 0.2 20.0 0.1 0.1 12.2 0.20 0.40 10 4741.00 2.1 1.1 1. 0 0.0 22.0 0.0 1.0 10.0 0. 0 2. 01 10.00 32. 00 3.1 2.12 2 0. 0 22. 0 0.3 0. 0 70. 3 1.0 1.20 0.00 20.21 0.0 0.0 3.0 .2 24.20.2 0.0 14.0 8: g; 0. 31 1. 30 0. 00 20. 0 21. 0 10.0 0. 0 24.1 0. 0 1.0 14. 0 95g 0. 24 0. 00 3. 00 30. 0 32.0 10 0 0. 0 22. 0 0.1 0. 0 70. 0kg 0.22 0.10 3.20 33.1 30.3 n4 0.1 as 0 0 1 0.0 10.1 1 0.20 0.00 4.1220.0 01.0 17.0 0.0 23.2 0.1 0 0 10.2 3 0.20 0.12 2.73 31.1 33.0 20.0.0.1 23.1 0.1 0 0 10.0 1.00 21.41 13.44 0.1 22.0 0.0 1 2 10.1 0.20 0.0010.04 .11. 1.2 1 1.4 1.4 00 22.3 0.1 00 10.0 0.0 4.01 14.02 00.00 1. 01.0 1.0 0 0 23.3 0.0 0 1 10.0 1.0 0. 1 0.41 .20 2.3 2.0 20 00 20.4 0.2 13 10.1 3 0. 71 1. 04 0.10 10.4 14.1 12.0 0 1 24.4 0. 0 o 1 14. 0 95g 0.01 1.40 4.30- 14.0 10.4 100 0 0 20 7 0.0 0.4 10.0 3% 0.40 1.33 3.00 10.120.0 10.0 0 0 24. 2 0.0 0 0 10.3 f? 0.02 1. 4.00 14.2 10.4 10.1 0 0 2200.0 0 1 7a 7 3 0. 00 1. 23 3.13 14.0 22. 3 2a 0 0 0 23. 4 0 0 0. 2 1a 41.47 27.17 12. 70 0.1 23.0 0.1 1.0 10.0 0.20 0.00 10.00 04.32 .2 1.4 1.30.1 23.2 0.2 1.0 101 8% 1.00 2.10 1.02 0.0 0.1 10. 0 1 21.7 0.1 0 0 10.20.12 1. 00 0. 01 10.4 13.1 14.3 o 0 20. 0 0. 0 0 3 7a 0 20 ig- 0.01 1.023.01 14.0 11.0 10.0 0.0 24.0 0.1 0 3 10.1

1 Average 012 or more runs.

Buns 5-12, CHOh is chloroform.

Runs 14-21, 01300]; is progylene dichloride.

Runs 23-26, 0030010 in ,2, trichlor propane. I uated vessel until thepressure in the vessel approximated atmospheric pressure. The reactionwas permitted to proceed in the closed reactionvessel while thetemperature was maintained at 500 C. until a pressure increase of 25percent above the initial pressure was observed. whereupon 'the reactiongases were rapidly removed from the reactor and analyzedn In some runswhere the acceleration'in reaction was extremely rapid the pressureincrease somewhat exceeded 25 percent before the reaction wasterminated.

A number of runs were also made without any sensitizer and other runswere made using only a poly-chlorinated parafiln and only bromine assensitizer.

In each of the runs the initial pressure was calculated, a pressurereading was made 0.5 minute after the run began, thereafter pressurereadings were made at intervals of 1 minute from the beginning or therun until 6 minutes thereafter, from that point readings were made at 2minute intervals until 20 minutes after the run began, and when it wasnecessary to run in excess or 20 minutes to obtain 25% pressureincrease,readings were taken at 5 minute intervals during the period from 20 to40 minutes and 70 hydrocarbon gives.

The sensitization factors recorded in the table are obtained by dividingthe time required for a particular pressure increase without .sensitizerby the time required for the same pressure increase with sensitizer.

By referring to the table. it is evident that chloroform, propylenedichloride and 1.2,3-tri- 00 combination of bromine with apoly-chlorinated hydrocarbon, the sensitizing eifectv is much greaterthan can be anticipated from the additive effect of the chlorinatedhydrocarbons and bromine when used alone. In fact, the mixture 05 of asmall amount of a poly-chlorinated hydrocarbon with bromine willincrease the sensitizing effect of the bromine far. above the valuewhich an amount of bromine equivalent to the combined amounts of bromineand chlorinated For example. one-half percent of bromine (run 3) gave asensitization factor for 25 percent pressure increase ,of 6.2; whereas,.25 percent of bromine mixed with .25 percent of chloroform (run 8) gavea sensitizaat l0 minute-intervals beyond 40 minutes until tion factor or10.5. Similarly, 0.25 percent of one-half percent of bromine.

. bromine mixed with 0.25 percent of propylen dichloride (run 17). gavea sensitization factor for 25 percent pressure increase of 12.8, asagainst 6.2 for one-half percent of bromine. A mixture of bromine andl,2,3,-trichloropropane in amounts of .25 percent each (run 24) gave asensitization factor of 10.4 as against 6.2 for Thus, it 'is apparentthat the poly-chlorinated hydrocarbons which are poorer sensitizer thanbromine when used alone, enhance the sensitization eifect of brominewhen mixed therewith to an extent considerably above that of 'anequivalent amount of bromine alone.

In order to further demonstrate the remarkable enhancement insensitization obtained by using a mixture of bromine andpoly-chlorinated aliphatic hydrocarbon. curves were plotted for severalruns with time in minutes as abscissae and pressure increase asordinates.

Referring to Figure 1, curve I is a curve for the average of severalblank runs, data for which is given in the table under run No. 1. Curve2 is the curve based on data recorded for run No. 2. Curve 3 is thecurve for data recorded in run No. 5. Curve 4 represents thehypothetical or additive results which would be expected from using amixture, of .25 mole percent of chloroform and .25percent of bromine assensitizer, and is obtained by adding the pressure increase withoutsensitizer at a selected time (from curve I), the pressure increase overthat of the blank run caused at the same time by the presence ofchloroform alone (curve 3 minus curve I) andthepressure increaseoaused'at the same time by the presence of bromine alone (curve 2 minuscurve I), and plotting on the graph the figures obtained for asufiicient number of different time periods to be able to draw a curvethrough the points. As an example, referring to Figure 1, at a timeapproximately 7 minutes after the beginning of the run, pressureincrease without any sensitizer (obtained from curve I) is 4.8 percent.At the same time the pressure increase in the run sensitized bychloroform alone is 7.5 percent (obtained from curve 3) and the pressureincrease in the run sensitized by bromine 'alone is 14.7 (obtained fromcurve 2). Pressure increase due to the. presence of chloroform istherefore, 7.5 minus 4.8 or 2.7 percent. Pressure increase due to thepresence of bromine is, therefore, 14.7 minus 4.8 or 9.9 percent. Thepressure increase that might be expected from the combination ofchloroform and bromine at a time seven minutes after the run begins isthe sum of the pressure increase at the same time without sensitizer andthe pressure increases caused by each of the sensitizers or 4.8 plus 2.7plus 9.9 or 17.4 percent. By referring to curve 4, it will be seen that7 minutes after the run begins the pressure increase is approximately17.4 percent. 5

Curve 5 represents the actual experimental data obtained in the runusing the combination sensi tizer. At a period 7 minutes after the runbegan, it will be seen that the actual pressure increase was 25 percentas against an expected increase of 17.4 percent.

Considering the effect in another way, in order to get a pressureincrease of approximately25 percent, it was necessary to permit thereaction to continue for a period of 7 minutes, whereas from theadditive results of theindividual sensi tizers, this pressure increasewould not have been expected v until the reaction had continued forapproximately 13 minutes.

Referring now to Figure 2, the curves are similar to those in Figure 1,with the exception that the data .are recorded in connection with amixture of bromine and propylene dichloride. As is apparent from thecurves, the sensitization factor of a mixture of bromine and propylenedichloride in amounts of .25 percent each is even greater than that ofthe mixture of bromine and chloroform. The same is true for the mixtureof bromine and 1,2,3-trichloropropane, results of which are showngraphically in Figure 3.

In order to further demonstrate the effectiveness of mixtures of bromineand poly-chlorinated aliphatic hydrocarbons in the ensitization ofhydrocarbons, Pennsylvania gas oil was subjected to cracking in acontinuous laboratory cracking apparatus at 525 C. under approximatelyatmospheric pressure at a through-put of approximately 165 grams ofcharging stock per hour. In a run in which no sensitizer was used, usinga oncethrough operation, 10.7 percent by weight of gas oil was convertedto liquid hydrocarbon boiling below 400 F. and 6.2 percent by weight wasconverted to gas. Under similar conditions using a mixture of 0.1percent by weight of bromine and 0.5 percent by weight of propylenedichloride,-

14.8 percent by weight of the gas oil was converted to liquidhydrocarbon boiling below 400 F. and 9.1 percent by weight of the gasoil was converted to gas. Under the same conditions a mixture of 0.1percent by weight of bromine and 0.5 percent by weight of1,2,3-trichloropropane converted 15.6 percent by weight of the gas oilto liquid hydrocarbon boiling below 400 F. and 9.7 percent by weight ofthe gas oil to gas.

From the analyses of the reaction products appearing in the table, thereaction is predominantly one of splitting the carbon to carbon bond asshown by the relatively large amount of unsaturated hydrocarbons formedand the small amount of hydrogen formed in the reaction. The natureof'the reaction products obtained is essentially the same regardless ofwhether or not sensitizer is used.

The invention is useful in connection with known types of mineral oilthermal cracking without catalyst. It is also useful in catalyticcracking operations wherein a known solid comminuted catalyst, such asnatural or synthetic aluminasilica compositions, is used. The inventionmay also be used in connection with cracking of gases to makeunsaturated hydrocarbons, such as cracking of propane to ethylene,cracking of butane to ethylene and propylene or the cracking of liquidhydrocarbons to olefins or diolefins such as butadiene.

Wherever the terms poly-chlorinated aliphatic hydrocarbon orpoly-chlorinated paraflin areused, they are intended to includecompounds in which all hydrogen has been replaced by chlorine atoms, asfor example, carbon tetrachloride, hexachlorethane and octachlorpropane.

This application is a continuation-in-part of our application Serial No.521,596, filed February 9, 1944, entitled Hydrocarbon conversion.

It is claimed:

1. The method of cracking hydrocarbons comprising subjectin hydrocarbonsto suitable crack.- ing conditions of time, temperature and pressure inthe presence of a small amount of a halogen selected from the groupconsisting of bromine and iodine and a small amount of apoly-chlorinated aliphatic hydrocarbon.

7 v 2. Method in accordance with claim 1 in which the halogen is bromineand the poly-chlorinated aliphatic hydrocarbon i a poly-chlorinated par-3. Method in accordance with claim 1 in which the amount of halogenpresent is at least .005 mole percent and the amount of poly-chlorinatedaliphatic hydrocarbon is,..at least .05 mole percent.

4. Method in accordance with claim 1 in which the minimum amount ofhalogen and poly-chlorinated aliphatic hydrocarbon present is about .005and .05 mole percent, respectively, and the maximum combined amount ofthe two is about 5 mole percent.

5. The method 01' cracking hydrocarbons con- ,taining at least 3 carbonatoms per molecule comrinated. aliphatic hydrocarbon is not less than.05 mole percent and the maximum combined 9. Method in accordance withclaim 5 in which the bromine is present in an amount ofapproximately .03to 2 mole percent and the polychlorinated hydrocarbon is present inamounts or approximately 0.25 to 2 mole precent.

10. The method of cracking C4 hydrocarbons comprising subjecting saidhydrocarbons to temperatures of the order of 500-750 C. in the presenceof small amounts of bromine and a poly-chlorinated aliphatichydrocarbon.

11. Method in accordance with claim 10 in which the amount of bromine isnot less than .005 mole percent and the amount 01' poly-chloamount of,the two is about 5 mole percent.

12. Method in accordance with claim 5 inwhich the hydrocarbons arenormally liquid hydrocarbone. 7

13. The method of "cracking hydrocarbon oil comprising subjecting saidoil to temperatures within the range of approximately 375 to 750C. inthe presence of a mixture of bromine. and a poly-chlorinated aliphatichydrocarbon, the bro-.

mine being present in amount not less than .03" mole per cent and thepolychlorinated aliphatic hydrocarbon being present in an amount notless than 0.25 mole per cent, the'combined amount of the bromine andpolychlorinated aliphatic hydrocarbon being less than 1% by weight ofthe oil.

14. Method in accordance with claim 13 in which the amount of bromine isabout 0.1% by weight of the oil and the amount of polychlorinatedaliphatic hydrocarbon is about 05% by weight 01. the oil. 7

15. Method in accordance with claim 13 in which the polychlorinatedaliphatic hydrocarbon is 1,2,3-trich1oropropane.

16. Method in accordance with claim 13 in which the polychlorinatedaliphatic hydrocarbon is propylene chloride.

- HILLIS O. FOLKINS.

CARLISIE M. THACKER.

. REFERENCES crrEn The following references are of record in the file ofthis patent:

- UNITED STATES PATENTS Number Name Date 2,221,952 Pier et a1. Nov. 19,1940 1,925,421 Van Peski Sept. 5, 1933 2,122,903 Winkler July 5, 19382,063,133 Tropsch Dec. 8, 1936 2,213,345 Marschner Sept. 3, 1940

